Sir, – I wish to respond to a letter from Professor James JA Heffron and William J Reville (June 19th) on the scientific evidence demonstrating the impairment effects of alcohol on driving.
The professors ask the question “at what lower blood alcohol level (BAC) does driving impairment set in?” The best available scientific evidence (including multitudes of epidemiological, experimental and review studies) can tell us. That question has been answered by Moskowitz & Robinson (1988), which summarised 177 global studies on the subject for example. It found that impairment sets in from 20mg onwards.
A further study by Moskowitz & Fiorentino (2000) summarised 112 studies. This study concluded that impairment was reported by more studies in this review for lower BAC levels than in the 1988 review by Moskowitz and Robinson. It finds that there is “strong evidence that impairment of some driving-related skills begins with any departure from zero BAC”.
Zador et al (2000) also estimates that the risk of being involved in a fatal crash for drivers at BAC levels as low as 20mg to 40mg is anywhere from two times to five times higher than for drivers with zero BAC. The risk of a fatal crash is four to 10 times greater at BACs between 50mg and 70 mg compared to drivers with zero BAC.
Against these hundreds of research papers, the letter-writers from UCC offer a single study by way of rebuttal. Or to be precise, one line from a study from New Zealand to support their opinions. Nowhere in their discussion did the authors of the New Zealand study dispute the findings of the numerous prior studies’ findings that a BAC of 50-80mg had adverse effects on driving.
This study also reported that drivers with a BAC of 50mg did actually experience significant impairment in terms of their being more likely to drive across the centre line, and more often, than those who received an alcohol placebo.
The same authors also conducted a similar simulator-based study in 2015, where they reported that drivers with a BAC of 50mg reported significant impairments in crossing the centre line for longer, and poorer lane-keeping in general, than those receiving an alcohol placebo.
In response to their “auto-brewery syndrome” assertions, this is a very rare phenomenon and has not been raised at all, or at least not successfully, in any reported driving under the influence case in Ireland in the past 20 years.
On their point that the “BAC legal limit is 80mg in the United States and England and Wales”, the limit is 50mg in the majority of other EU member states. Scotland and Northern Ireland are moving to 50mg. And it is also 50mg in the country of the study they cite, New Zealand, for all drivers, and zero for drivers under 20 years of age.
The professors mention that the "proposed legislation applies the 'one size fits all' standard to the penalties". That is correct. That is the basis of our drink driving laws (per se limit) as it does not account for individual gender, biological or physiological differences between drivers.
In the final paragraph of their letter, the professors state that “it must also be appreciated that losing one’s driving license, even for three months, can be an enormous burden’”. We would clarify that this is the actual point of this sanction; it is a serious offence to drive while over the legal limit, and the penalty needs to reflect the seriousness of the crime.
Driving is not a right, it is a privilege. And when you receive your licence, it is on the agreement that you will drive safely, not endanger the lives of others, and drive in accordance with the law.
In Sweden, a country with one of the lowest road death rates in Europe, driving with a BAC level between 20 and 99mg can result in licence disqualification for 12 months, a fine (proportionate to daily income) and the potential for imprisonment.
It is time our drink driving laws caught up with the public’s attitudes and sent a clear signal to the minority who are slow to change that drink driving is not normal social behaviour under any circumstances. – Yours, etc,
MOYAGH MURDOCK,
Chief Executive,
Road Safety Authority,
Moy Valley Business Park,
Primrose Hill,
Ballina, Co Mayo.